Rapidly Quenched Kosterlitz-Thouless Superfluid Transitions

Rapidly quenched Kosterlitz-Thouless (KT) superfluid transitions are studied by solving the Fokker-Planck equation for the vortex-pair dynamics in conjunction with the KT recursion relations. Power-law decays of the vortex density at long times are found, and the results are in agreement with a scaling proposal made by Minnhagen and co-workers for the dynamical critical exponent. The superfluid density is strongly depressed after a quench, with the subsequent recovery being logarithmically slow for starting temperatures near T$_{KT}$. No evidence is found of vortices being ''created'' in a rapid quench, there is only decay of the existing thermal vortex pairs.Comment: 4 pages, 5 figures, revtex4, version accepted for PR

Vortex Core Size in 3^3He-4^4He films with Monolayer Superfluid 4^4He

The superfluid transition of $^3$He-$^4$He mixture films adsorbed on alumina powder is studied, with a $^4$He superfluid coverage near one layer. With up to 1.3 layers of $^3$He added, the transition becomes strongly broadened, indicating a linear increase in the vortex core size for $^3$He coverages below one layer. Annealing of the sample mixture at 4.2 K is found to be critically important in ensuring a homogeneous film across the porous substrate.Comment: 2 pages, 2 figures, accepted for LT22 Conference Proceedings, Physica

Emergence of Gapped Bulk and Metallic Side Walls in the Zeroth Landau level in Dirac and Weyl semimetals

Recent transport experiments have revealed the activation of longitudinal magnetoresistance of Weyl semimetals in the quantum limit, suggesting the breakdown of chiral anomaly in a strong magnetic field. Here we provide a general mechanism for gapping the zeroth chiral Landau levels applicable for both Dirac and Weyl semimetals. Our result shows that the zeroth Landau levels anticross when the magnetic axis is perpendicular to the Dirac/Weyl node separation and when the inverse magnetic length $l_B^{-1}$ is comparable to the node separation scale $\Delta k$. The induced bulk gap increases rapidly beyond a threshold field in Weyl semimetals, but has no threshold and is non-monotonic in Dirac systems due to the crossover between $l_B^{-1}>\Delta k$ and $l_B^{-1}<\Delta k$ regions. We also find that the Dirac and possibly Weyl systems host counterpropagating edge states between the zeroth Landau levels, leading to a state with metallic side walls and zero Hall conductance.Comment: 8 pages, 4 figure

Polyyne Ring Nucleus Growth Model for Single-Layer Carbon Nanotubes

We propose, based on recent experimental results, a polyyne ring nucleus (PRN) growth model for the synthesis of single-layer nanotubes (SLN's). The PRN model assumes that (i) the critical nuclei are the planar carbon polyyne rings that are observed to be most stable for sizes in the range C10 to C40; (ii) ComCn clusters (possibly charged) play the role of a catalyst by serving to add C2 or other gas phase species into the growing tube; (iii) promoters such as S, Bi, and Pb serve to modify the rates for these processes by stabilizing the ring structure. We suggest experiments to test and amplify this PRN model, including a flow tube arrangement that might be useful for synthesizing more uniform SLN's

Uncertainty Propagation and Feature Selection for Loss Estimation in Performance-based Earthquake Engineering

This report presents a new methodology, called moment matching, of propagating the uncertainties in estimating repair costs of a building due to future earthquake excitation, which is required, for example, when assessing a design in performance-based earthquake engineering. Besides excitation uncertainties, other uncertain model variables are considered, including uncertainties in the structural model parameters and in the capacity and repair costs of structural and non-structural components. Using the first few moments of these uncertain variables, moment matching requires only a few well-chosen point estimates to propagate the uncertainties to estimate the first few moments of the repair costs with high accuracy. Furthermore, the use of moment matching to estimate the exceedance probability of the repair costs is also addressed. These examples illustrate that the moment-matching approach is quite general; for example, it can be applied to any decision variable in performance-based earthquake engineering. Two buildings are chosen as illustrative examples to demonstrate the use of moment matching, a hypothetical three-story shear building and a real seven-story hotel building. For these two examples, the assembly-based vulnerability approach is employed when calculating repair costs. It is shown that the moment-matching technique is much more accurate than the well-known First-Order-Second-Moment approach when propagating the first two moments, while the resulting computational cost is of the same order. The repair-cost moments and exceedance probability estimated by the moment-matching technique are also compared with those by Monte Carlo simulation. It is concluded that as long as the order of the moment matching is sufficient, the comparison is satisfactory. Furthermore, the amount of computation for moment matching scales only linearly with the number of uncertain input variables. Last but not least, a procedure for feature selection is presented and illustrated for the second example. The conclusion is that the most important uncertain input variables among the many influencing the uncertainty in future repair costs are, in order of importance, ground-motion spectral acceleration, component capacity, ground-motion details and unit repair costs

Early Delirium Assessment for Hospitalized Older People in Indonesia: a Systematic Review

Background: Due to the increasing risk of getting co-morbidity and frailty, older people tend to be prone to hospitalization. Hospitalization in older people brings many adverse effects. Moreover, when these elderly get delirium, the mortality and morbidity will increase. The risk of getting deterioration and worsening condition because of delirium would also increase. In fact, delirium assessment is not a high priority in taking care older people during hospitalization because the focus of care is treating the disease.Delirium screening as an early recognition of delirium in the hospitalized elderly inIndonesia remains unreported and even do not well evaluated. Therefore, delirium as a preventable problem or causing problems remains unrecognized.Purpose: This paper aims to review the current evidence of early assessment of delirium in hospitalized older people.Methods: A systematic review was conducted from four databases yielding to 4 articles which met the inclusion and exclusion criteria.Results: There are four focuses on the result, namely delirium screening tools, patient characteristics, identified early delirium assessment, and outcomes affected by early delirium assessment. Confusion Assessment Method (CAM) was used as the delirium screening tool in the hospital. Establishing the care team involving many disciplines will give a better way to improve the integrated care and collaborative care.Conclusion: Performing CAM integrated into comprehensive geriatric assessment can be the most important thing to be undertaken when looking after the hospitalized elderly

An overture for well-tempered regulators: four variations on a LETR theme

This paper is a development of the Association of Law Teachers� annual Lord Upjohn lecture, delivered on 29 January 2015 at City Law School, London, by the principal investigators of the Legal Education and Training Review�s (LETR) research team. In it, each of the authors takes a different theme arising from the LETR Report, and explores its implications and application, focusing on research and innovation; access and flexibility; deprofessionalisation, and, finally, reflecting on the way the Report addressed themes of common training, oversupply and access to justice. As our title indicates, the paper comprises both individual performances and performance as a consort, and we hope that in this way, we enact one of our key themes: the social nature of legal education and its regulation

Development of EHD Ion-Drag Micropump for Microscale Electronics Cooling Systems

In this investigation, the numerical simulation of electrohydrodynamic (EHD) ion-drag micropumps with micropillar electrode geometries have been performed. The effect of micropillar height and electrode spacing on the performance of the micropumps was investigated. The performance of the EHD micropump improved with increased applied voltage and decreased electrode spacing. The optimum micropillar height for the micropump with electrode spacing of 40$\mu$m and channel height of 100$\mu$m at 200V was 40$\mu$m, where a maximum mass flow rate of 0.18g/min was predicted. Compared to that of planar electrodes, the 3D micropillar electrode geometry enhanced the overall performance of the EHD micropumps.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Statistically Preserved Structures and Anomalous Scaling in Turbulent Active Scalar Advection

The anomalous scaling of correlation functions in the turbulent statistics of active scalars (like temperature in turbulent convection) is understood in terms of an auxiliary passive scalar which is advected by the same turbulent velocity field. While the odd-order correlation functions of the active and passive fields differ, we propose that the even-order correlation functions are the same to leading order (up to a trivial multiplicative factor). The leading correlation functions are statistically preserved structures of the passive scalar decaying problem, and therefore universality of the scaling exponents of the even-order correlations of the active scalar is demonstrated.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let